Q: Boron can help with insect pressure, but is there a concern about applying too much?
A: I am of the persuasion that if boron were used in adequate levels, insecticide use would be cut by greater than 90 percent. And so I find it interesting that boron is the one element that we’re constantly warned against using.
It is true that boron can become toxic when there isn’t enough calcium in the system. Our rule of thumb is that in order to grow exceptionally healthy crops, you need a minimum of a 1,000 ppm calcium and 3 ppm boron in the soil.
We’ve learned from William Albrecht and from Neil Kensey and from many other very esteemed agronomists that we need to balance our soil minerals from the perspective of base saturation percentage. This is very important work that has taught us a lot. But in light, sandy soils — when you have CECs below 10 — you still need the optimal mineral ratios, but you also need to consider minimum part per million concentrations — not simply percent base saturation. The minimum thresholds that you need for a high-yielding, healthy crop are 1,000 ppm calcium, 150 ppm magnesium and 125 ppm potassium. The ratios are very important, but historically we have not paid enough attention to minimum thresholds, particularly in the case of calcium, because it’s often the first one to not meet the threshold.
If you have soils that have less than 1,000 ppm calcium, it is possible to produce a boron toxicity. But if you have enough calcium in your soils, you do not need to be worried about producing a boron toxicity.
The most effective way — and the least expensive way — to supply adequate levels of boron is to apply it to the soil. When we apply boron to the soil, it facilitates microbes extracting calcium and incorporating calcium into microbial cells and then transporting calcium into the plant through the rhizophagy process.
From John Kempf’s Eco-Ag U session at the 2024 Acres U.S.A. conference.
